The overall objective of this research is to investigate glucose and lactate metabolism in hospitalized patients with malignant solid tumors, particularly colo-rectal cancer. Using isotope tracer infusion techniques, the production, oxidation and recycling of glucose via lactate will be measured under standardized conditions. This data will be correlated with the presence or absence of carbohydrate intolerance following an oral glucose load. Preliminary data on the metabolic response of cachetic patients to an ingested protein meal will be extended and incorporated into planned work with alanine turnover studies. This data on abnormal responses to ingested protein may provide a rational basis from which improvements, concurrent therapy and support may be achieved.